Guide to printing students
-Few objective Questions and answers-
Written by : N.R. Jayaraman
The articles are meant to help the students gain knowledge and effectively compete in the interviews and nothing else. Please note that these are not to be published by anyone for commercial purpose without the written permission from the author since the theme and illustrative examples have been compiled exclusively by the author for the benefit of the student community. THIS WILL BE PERIODICALLY PUBLISHED.
25) What type of ink is used in Intaglio printing process?
The pigmentation of Intaglio ink is very high. The varnish used have higher tackiness compared to other processes. The quality of the ink used in Intaglio is such that it remains slightly loosened (less viscous) while inking the plate due to heat generated in the ink fountain (heat apparatus fitted) and the plate cylinder inside which heating elements are fitted. The ink slowly dries on the substance on which it is printed by slight penetration cum oxidation cum polymerization process- one after the other taking place in quick succession to ensure that the relief effect of the ink required is not lost. Normally the standard Intaglio ink takes 2-3 clear days to dry and therefore in order to prevent set off on the backside of the printed substances, the same are interleaved with unpolished Kraft sheets like how the art papers are interleaved in Letterpress process of printing.
26) Why do you need heating elements in the Ink fountain and Plate cylinder on Intaglio machines?
The Ink used in Intaglio process is very stout and can not be even taken out by ink knives from the ink tins and are to be sucked by powerful ink sucking units fitted with heavy tubes that flows the ink into the ink duct.
In order to ensure that the ink filled in the ink duct gets agitated freely for uniform inking, the very stout ink need to be slightly loosened for a while till they are supplied to the special rollers that inks the plate cylinder. The engraved images in the plate cylinder has to also get filled with the loosened ink and then transfer the entire ink deposited in the pits on to the surface of the paper.
Once the ink is transferred on to the paper, it has to immediately start shedding its loosened form and to turn into its true (stout) form. Therefore in order to convert the original form of stout ink into temporary free flowing ink till they are transferred on to the paper, temporary heating arrangement is needed for purpose stated as above.